1. Field of the Invention
The present invention refers to a semiconductor manufacturing equipment, and more particularly, to a semiconductor wafer baking apparatus. The semiconductor wafer baking apparatus includes an exhaust heat compensator to compensate a temperature in an edge area of a wafer and to prevent a temperature drop in the edge area of the wafer while the wafer is baked at a desired temperature during manufacturing process thereof. The semiconductor wafer baking apparatus uniformly maintains the temperature of the wafer surface.
2. Description of Related Art
In semiconductor manufacturing processes, for example, a wafer baking process in a desired temperature after a photoresist coating process in photolithography, semiconductor wafers are treated one by one. The wafer baking process in a semiconductor manufacturing process includes a pre-coating bake, a soft bake, a post-exposed bake, and a hard bake. The pre-coating bake process eliminates moistures absorbed in a wafer before coating a photoresist. The soft bake process employing a heated hot plate heats a wafer to release a shear stress caused by coating the photoresist and a solvent. The post-exposed bake recovers instability in a chemical structure of the photoresist generated in an area developed by ultraviolet scattering. The hard bake solidifies the photoresist after a pattern developing process in a wafer.
Baking a semiconductor wafer employs a heating plate for heating a wafer. Then, the uniformity of a process temperature in a wafer determines the uniformity of a pattern size in the wafer.
FIG. 1 illustrates a configuration of a conventional wafer baking apparatus.
The conventional wafer baking apparatus includes a heating plate 1, a wafer supporter 2, a wafer guide 3, a chamber body 4, and a cover 5. The heating plate 1 heats a wafer W. The wafer supporter 2 keeps a distance between the wafer W and the heating plate 1. The wafer guide 3 enables a proper arrangement of the wafer W on the heating plate 1. The chamber body 4 surrounding the heating plate 1 and the wafer guide 3, moves up and down in vertical direction. The cover 5 placed in an upper side of the wafer guide 3 moves up and down in vertical direction. The chamber body 4 and the cover 5 stabilize temperatures and aerodynamic flows in the wafer baking apparatus.
The wafer supporter 2 is preferably a cylindrical type of the same size as the heating plate 1. The wafer supporter 2 is installed in the upper side of the heating plate 1 or includes a plurality of protrusions in the upper area of the heating plate 1. Preferably, the wafer supporter 2 loads a wafer in a distance of 100 to 200 xcexcm spaced from the heating plate 1 and maintains the distance constantly and uniformly regardless of the position of the heating plate 1. One side of the wafer guide 3 contacting the wafer W forms a slope 3a. The conventional semiconductor baking apparatus as shown in FIG. 1 operates as follows.
The chamber body 4 moves down and the cover 5 moves up so that a wafer transfer arm (not shown in FIG. 1) can load the wafer W on the heating plate 1. Then, the slope 3a of the wafer guide 3 leads the wafer W to be placed on the wafer supporter 2 properly. After the wafer W is placed on the wafer supporter 2, the chamber body 4 moves up and the cover 5 moves down, so that the chamber body 4 and the cover 5 become in contact with each other. Then, the heat transferred from the heating plate 1 preheated to a temperature is used for baking the wafer W loaded on the wafer supporter 2.
After baking the wafer W at a constant temperature and for a predetermined time, the cover moves up and the chamber body 4 moves down so that the wafer transfer arm extracts the baked wafer W from the wafer supporter 2. Such a process is performed in repeat to bake another wafer.
However, the wafer W baked by the heat transferred from the heating plate 1 is exposed in the air and the heat transferred to the wafer W is exhausted to the air. Therefore, the temperature distribution of the wafer W is not uniform. In other words, as illustrated in FIG. 2, the heat exhausted from the edge area of the wafer W is more than that from the center area of the wafer W. Therefore, the temperature of the wafer W is lowered toward the edge area from the center area of the wafer W. As a result, uniform micro patterns in the wafer W can not be created precisely, and device characteristics between the center and the edge area of the wafer W are different from each other, which eventually results in a yield drop.
To overcome the above-described problems, preferred embodiments of the present invention provide a semiconductor wafer baking apparatus for preventing heat exhaustion from an edge area of a wafer and for uniformly maintaining temperatures of the wafer.
In order to achieve the above object, one aspect of the present invention provides a semiconductor wafer baking apparatus comprising a heating plate, a wafer guide, and an exhaust heat compensator. The heating plate is loaded with a wafer and the wafer guide properly arranges the wafer on or above the heating plate. The exhaust heat compensator is placed on the wafer guide and compensates exhausted heat from an edge area of the wafer. The exhaust heat compensator comprises a penetration hole exposes a center portion of the wafer.
In order to achieve the above object, another aspect of the present invention provides a semiconductor wafer baking apparatus comprising a heating plate, a wafer supporter, and an exhaust heat compensator. The heating plate is loaded with a wafer and heats the wafer to a predetermined temperature. The wafer supporter keeps a distance between the wafer and the heating plate so that the wafer does not contact directly with the heating plate. The exhaust heat compensator is placed on the top side of the heating plate to surround an edge area of the wafer to compensate the temperature of the edge area of the wafer.